Mount Everest Death Toll at Four with One Missing

It was rush hour on Mount Everest this weekend with 150 climbers reaching the summit, including a 73-year-old woman, but the world's tallest peak also claimed the lives of four climbers, and one more is missing.

The first stretch of clear weather during the spring climbing season spurred the rush of climbers to crowd the trails leading to the 29,029-foot peak, which spans the borders of China, Nepal and Tibet.

The resulting traffic jam of people may have contributed to the deaths, according to the Associated Press.

Eberhard Schaaf, a 61-year-old German doctor, Nepal-born Canadian Shriya Shah and South Korean mountaineer Song Won-bin died on Saturday as they descended the mountain after suffering from exhaustion and altitude sickness, Gyanendra Shrestha of Nepal's Mountaineering Department told the AP.

Chinese climber Ha Wenyi and South Korean mountaineer Song Won-bin also died Saturday while descending the mountain, the AP reported.

A Chinese national is still missing, but a Nepalese Sherpa guide are who had been reported missing is safe and has reached the base camp, according to Shrestha.

"There was a traffic jam on the mountain on Saturday. Climbers were still heading to the summit as late as 2:30 p.m. which is quite dangerous," Shrestha told the AP.

"With the traffic jam, climbers had a longer wait for their chance to go up the trail and spent too much time at higher altitude. Many of them are believed to be carrying limited amount of oxygen not anticipating the extra time spent," Shrestha said.

An estimated 150 climbers reached the summit over the weekend. Among them was Tamae Watanbe, who at 73 became oldest woman to scale the peak of Mount Everest on Saturday, breaking her own record set a decade ago when she reached the top of the mountain at the age of 63, reported the Associated Press.

Watanbe, a seasoned climber from Japan, scaled the Tibetan northern side of the mountain and set off for the summit from the final high altitude camp around 8:30 p.m. on Friday. She and her team, which included Noriyuki Muraguchi, also from Japan, and three other climbing sherpas, reached the top of the peak around 7 a.m. on Saturday, according to Asian Trekking, the expedition company she teamed with to complete the journey.

Watanbe has climbed of the world's most treacherous mountains over the last few decades, including five other mountains reaching more than 26,000 feet above sea level, according to Asian Trekking's website.

The oldest man to reach the summit is Min Bahadur Sherchan of Nepal, who was 76 when he made the climb in 2008.

Climbing conditions at Mount Everest have been particularly rough this season due to heavy snowfall and winds, Shrestha told Agence France-Presse.

"We're not sure quite what accounts for this unusual acuity - probably several different factors contribute, including more trekkers overnighting in base camp (more folks novice to sleeping at such high altitude and the complications that ensue), more teams signing on for our service, a warm and unstable season, a particularly treacherous icefall route, and more helicopters than we've ever seen available for quick response," the site said.